Summary:
The gbm_surface is owned by the EglGbmBackend, but it's not the only one
using it. The DrmSurfaceBuffer is also using it and needs it to destroy
the gbm_bo. Now this can become a problem in the following situation:
* a page flip is still pending
* the EglGbmBackend destroys the gbm_surface
-> when the page flip happens the DrmSurfaceBuffer will try to destroy
the gbm_bo and crash as the gbm_surface is no longer valid. This
situation can happen when switching screens or when switching compositing
backend (OpenGL 2 -> OpenGL 3).
To address this problem a class GbmSurface is added which wrapps the
gbm_surface pointer. The EglGbmBackend creates and holds a shared pointer
to the GbmSurface and passes that one to the DrmSurfaceBuffer. So when
cleaning up the gbm_surface only the shared pointer is reset and in case
the DrmSurfaceBuffer still needs it, it can access it without problems.
BUG: 385372
FIXED-IN: 5.11.0
Test Plan: Not yet
Reviewers: #kwin, #plasma, subdiff
Subscribers: plasma-devel, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D8152
Split off GBM based buffers to a separate file, which gets only included,
when GBM is available.
Note, that this also removes the gbmCallback, since already before this
patch we did delete the buffers always without it.
The plan is to later use this file for via GBM directly imported Wayland
buffers as well.
Test Plan:
Tested with Gl and QPainter backends.
Reviewers: #kwin
Subscribers: kwin, #kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D5179
